1. Field of the Invention
This invention relates to a data transfer device capable of transferring data such as audio data downloaded via a mobile communications network to an external device.
2. Description of the Related Art
A cellular telephone comprises a function of storing and playing audio data downloaded via a mobile communications network. The cellular telephone further comprises a close-range radio communications function such as Bluetooth conforming to Advanced Audio/Video Distribution Profile (Bluetooth™ SIG) and a function of transferring downloaded and stored audio data to an external device (hereinafter called a data transfer function).
The cellular telephone comprising the close-range radio communications function conforming to Advanced Audio/Video Distribution Profile (Bluetooth SIG) can serve as a remote controller to control the external device from a distance (hereinafter called a remote control function) or can be controlled by the external device from a distance.
The present inventor has developed a system employing the close-range radio communications function, wherein the external device requests the cellular telephone to designate or transfer the audio data by the remote control function and, in response to this request, the cellular telephone transfers the designated audio data to the external device by the data transfer function.
The present inventor has considered a system of establishing a remote control session between the cellular telephone and the external device to employ the remote control function and then establishing another remote control session therebetween to perform the data transfer function. In this system, for example, if the external device does not have the data transfer function, data is not transfer although the remote control session is established, and the remote control session may be maintained unnecessarily.
According to the prior art, if a packet communications link is established between two devices but no data is transferred via the link, the link is disconnected (refer to, for example, National Publication No. 2003-524961 and Jpn. Pat. Appln. KOKAI Publication No. 2002-368775). However, the technique disclosed in these documents is associated with a single session but is not associated with two sessions.
The conventional data transfer device has a problem that if two sessions are established to transfer the data, one of the sessions may be maintained although the data transfer is not executed.